Stainless Steel - General Information - Alloying Elements in Stainless Steel Stainless Steel - General Information - Alloying Elements in Stainless Steel Alloying Elements in Stainless Steel Stainless Steels comprise a number of alloying elements according to the specific grade and composition. Listed below are the alloying additions with the reason for their presence, whilst attched is a summary table. Carbon (C): Iron is alloyed with carbon lo make steel and has the effect of increasing the hardness and strength of iron. Pure iron cannot be hardened or strengthened by heat treatment but the addition of carbon enables a wide range of hardness and strength. In Austenitic and Ferritic stainless steels a high carbon content is undesirable, especially for welding due to the threat of carbide precipitation. Manganese (Mn): Manganese is added to steel to improve hot working properties and increase strength, toughness and hardenability. Manganese, like nickel, is an Austenite forming element and has been used as a substitute for nickel in the AISI200 Series of Austenitic Stainless Steels, e.g. AISI 202 as a substitute for AISI 304. Chromium (Cr): Chromium is added to steel to increase resistance to oxidation.

This resistance increases as more chromium is added. 'Stainless Steels have a minimum of 10.5% Chromium (traditionally 11 or 12%). This gives a very marked degree of general corrosion resistance when compared to steels with a lower percentage of Chromium. The corrosion resistance is due to the formation of a self-repairing passive layer of Chromium Oxide on the surface of the stainless steel. Nickel (Ni): Nickel is added in large amounts, over about 8%, to high Chromium stainless steels to form the most important class of corrosion and heat resisting steels. These are the Austenitic stainless steels, typified by 18-8 (304/1.4301), where the tendency of Nickel to form Austenite is responsible for a great toughness (impact strength) and high strength at both high and low temperatures. Nickel also greatly improves resistance to oxidation and corrosion. Molybdenum (Mo): Molybdenum, when added to chromium-nickel austenitic steels, improves resistance to pitting and crevice corrosion especially in chlorides and sulphur containing environments.

Nitrogen (N): Nitrogen has the effect of increasing the Austenite stability of stainless steels and is, as in the case of Nickel, an Austenite forming element. Yield strength is greatly improved when nitrogen is added to stainless steels as is resistance to pitting corrrosion. Copper (Cu): Copper is normally present in stainless steel as a residual element. However, it is added to a few alloys to produce precipitation hardening properties or to enhance corrosion resistance particularly in sea water environments and sulphuric acid. Titanium (Ti): Ttitanium is added for carbide stabilization especially when the material is to be welded. It combines with carbon to form titanium carbides, which are quite stable and hard lo dissolve in steel, which tends to minimise the occurrence of inter-granular corrosion. Adding approximately 0.25 / 0.60% titanium causes the carbon to combine with titanium in preference to chromium, preventing a tie-up of corrosion-resisting chromium as inter-granular carbides and the accompanying loss of corrosion resistance at the grain boundaries.

However, the use of titanium has gradually decreased over recent years due to the ability of steelmakers to deliver stainless steels with very low carbon contents that are readily weldable without stabilisation. Phosphorus (P): Phosphorus is usually added with sulphur, to improve machinability. The Phosphorus present in Austenitic stainless steels increases strength. However, it has a detrimental effect on corrosion resistance and increases the tendency of the material to crack during welding. Sulphur (S): When added in small amounts Sulphur improves machinability. However, like Phosphorous it has a detrimental effect on corrosion resistance and weldability. Selenium (Se): Selenium was previously used as an addition to improve machinability. Niobium / Colombium (Nb): Niobium is added to steel in order to stabilise carbon, and, as such, performs in the same way as described for Titanium. Niobium also has the effect of strengthening steels and alloys for high temperature service. SiIicon (Si): Silicon is used as a deoxidising (killing) agent in the melting of steel and as a result most steels contain a small percentage of Silicon.

Cobalt (Co): Cobalt becomes highly radioactive when exposed to the intense radiation of nuclear reactors, and, as a result, any stainless steel that is in nuclear service will have a Cobalt restriction, usually approximately 0.2% maximum. This problem is emphasized because there is normally a residual Cobalt content in the Nickel used in producing Austenitic stainless steels. Calcium (Ca): Small additions are used to improve machiniability, without the detrimental effects on other properties caused by Sulphur, Phosphorus and Selenium. Iron and steel - Introduction to their science, properties, uses Iron and steel Tweet by Chris Woodford . Last updated: July 14, 2016. Think of the greatest structures of the 19th century—the Eiffel Tower, the Capitol, the Statue of Liberty—and you'll be thinking of iron. The fourth most common element in Earth's crust, iron has been in widespread use now for about 6000 years. Hugely versatile, and one of the strongest and cheapest metals , it became an important building block of the Industrial Revolution, but it's also an essential element in plant and animal life.

Combined with varying (but tiny) amounts of carbon, iron makes a much stronger material called steel, used in a huge range of human-made objects, from cutlery to warships , skyscrapers, and space rockets. Let's take a closer look at these two superb materials and find out what makes them so popular! Photo: The world's first cast-iron bridge, after which the village of Ironbridge in Shropshire, England was named. It was built across the River Severn by Abraham Darby III in 1779 using some 384 tons of iron. You can read more about its history and construction on the official Ironbridge website. Photo by Jason Smith courtesy of Wikimedia Commons . What is iron like? Photo: A sample of iron from a meteorite (next to a pen for scale). From the mineral collection of Brigham Young University Department of Geology, Provo, Utah. Photograph by Andrew Silver courtesy of US Geological Survey Photographic Library . You might think of iron as a hard, strong metal tough enough to support bridges and buildings , but that's not pure iron. What you're thinking of is alloys of iron combined with carbon and other elements. Pure iron is a different matter altogether.

Consider its physical properties (how it behaves by itself) and its chemical properties (how it combines and reacts with other elements and compounds). Physical properties Pure iron is a silvery-white metal that's easy to work and shape and it's just soft enough to cut through (with quite a bit of difficulty) using a knife. You can hammer iron into sheets and draw it into wires. Like most metals, iron conducts electricity and heat very well and it's very easy to magnetize . Chemical properties The reason we so rarely see pure iron is that it combines readily with oxygen. Indeed, iron's major drawback as a construction material is that it reacts with moist air (in a process called corrosion) to form the flaky, reddish-brown oxide we call rust. Iron reacts in lots of other ways too—with elements ranging from carbon, sulfur, and silicon to halogens such as chlorine. Broadly, iron's compounds can be divided into two groups known as ferrous and ferric (the old names) or iron (II) and iron (III); you can always substitute "iron(II)" for "ferrous" and "iron(III)" for "ferric" in compound names.

In iron (II) compounds, iron has a valency (chemical combining ability) of +2. Examples include iron(II) oxide (FeO), a pigment (coloring chemical); iron (II) chloride (FeCl2), used in medicine as "tincture of iron"; and an important dyeing chemical called iron (II) sulfate (FeSO4). In iron (III) compounds, iron's valency is +3. Examples include iron (III) oxide (Fe2O3), used as the magnetic material in things like cassette tapes and computer hard drives and also as a paint pigment; and iron (III) chloride (FeCl3), used to manufacture many industrial chemicals. Sometimes iron (II) and iron (III) are present in the same compound. A paint pigment called Prussian blue is actually a complex compound of iron (II), iron (III), and cyanide with the chemical formula Fe4[Fe(CN)6]3. Photo: Iron in action: Chances are you're using magnetic iron (III) oxide right this minute in your computer's hard drive. Where does iron come from? Photo: Iron is essential for a healthy diet. That's why it's packed into many breakfast cereals.

A 100g portion of these cornflakes provides 14.0mg of iron—enough to meet a typical person's needs for one day. This amount of iron is called your recommended daily average or RDA. Here's a great little experiment from Scientific American to extract the iron from your cornflakes . Iron is the second most common metal in Earth's crust, after aluminum , but because it reacts so readily with oxygen it's never mined in its pure form (though meteorites are occasionally discovered that contain samples of pure iron). Like aluminum, most iron "locked" inside Earth exists in the form of oxides (compounds of iron and oxygen). Iron oxides exist in seven main ores (raw, rocky minerals mined from Earth): Hematite (the most plentiful) Siderite Taconite (a combination of hematite and magnetite). Different ores contain different amounts of iron. Hematite and magnetite have about 70 percent iron, limonite has about 60 percent, pyrite and siderite have 50 percent, while taconite has only 30 percent.

Using a combination of both deep mining (under the ground) and opencast mining (on the surface), the world produces approximately 1000 million tons of iron ore each year, with China responsible for just over half of it. Which countries produce the world's iron? Chart shows estimated figures for pig iron for 2015. In the United States, four companies currently produce pig iron in 11 different locations. Source: US Geological Survey, Mineral Commodity Summaries, January 2016. Types of iron Pure iron is too soft and reactive to be of much real use, so most of the "iron" we tend to use for everyday purposes is actually in the form of iron alloys : iron mixed with other elements (especially carbon) to make stronger, more resilient forms of the metal including steel. Broadly speaking, steel is an alloy of iron that contains up to about 2 percent carbon, while other forms of iron contain about 2–4 percent carbon. In fact, there are thousands of different kinds of iron and steel, all containing slightly different amounts of other alloying elements. Pig iron Basic raw iron is called pig iron because it's produced in the form of chunky molded blocks known as pigs.

Pig iron is made by heating an iron ore (rich in iron oxide) in a blast furnace: an enormous industrial fireplace, shaped like a cylinder, into which huge drafts of hot air are introduced in regular "blasts". Blast furnaces are often spectacularly huge: some are 30–60m (100–200ft) high, hold dozens of trucks worth of raw materials, and often operate continuously for years at a time without being switched off or cooled down. Inside the furnace, the iron ore reacts chemically with coke (a carbon-rich form of coal) and limestone. The coke "steals" the oxygen from the iron oxide (in a chemical process called reduction), leaving behind a relatively pure liquid iron, while the limestone helps to remove the other parts of the rocky ore (including clay, sand, and small stones), which form a waste slurry known as slag. The iron made in a blast furnace is an alloy containing about 90–95 percent iron, 3–4 percent carbon, and traces of other elements such as silicon, manganese, and phosphorus, depending on the ore used.

Pig iron is much harder than 100 percent pure iron, but still too weak for most everyday purposes. Cast iron Cast iron is simply liquid iron that has been cast: poured into a mold and allowed to cool and harden to form a finished structural shape, such as a pipe, a gear , or a big girder for an iron bridge . Pig iron is actually a very basic form of cast iron, but it's molded only very crudely because it's typically melted down to make steel. The high carbon content of cast iron (the same as pig iron—roughly 3–4 percent) makes it extremely hard and brittle: large crystals of carbon embedded in cast iron stop the crystals of iron from moving about. Cast iron has two big drawbacks: first, because it's hard and brittle, it's virtually impossible to shape, even when heated; second, it rusts relatively easily. It's worth noting that there are actually several different types of cast iron, including white and gray cast irons (named for the coloring of the finished product caused by the way the carbon inside it behaves).

Photo: One of the world's most famous iron buildings, the Capitol in Washington, DC has a dome made of 8,909,200 pounds of cast iron! Photo by courtesy of The Architect of the Capitol . Wrought iron Cast iron assumes its finished shape the moment the liquid iron alloy cools down in the mold. Wrought iron is a very different material made by mixing liquid iron with some slag. The result is an iron alloy with a much lower carbon content. Wrought iron is softer than cast iron and much less tough, so you can heat it up to shape it relatively easily, and it's also much less prone to rusting. However, relatively little wrought iron is now produced commercially, since most of the objects originally produced from it are now made from steel, which is both cheaper and generally of more consistent quality. Wrought iron is what people used to use before they really mastered making steel in large quantities in the mid-19th century. Types of steel Strictly speaking, steel is just another type of iron alloy, but it has a much lower carbon content than cast and wrought iron and other metals are often added to give it extra properties.

Steel is such an amazingly useful material that we tend to talk about it as though it were a metal in its own right—a kind of sleeker, more modern "son of iron" that's taken over the family firm! It's important to remember two things, however. First, steel is still essentially (and overwhelmingly) made from iron. Second, there are literally thousands of different types of steel, many of them precisely designed by materials scientists to perform a particular job under very exacting conditions. When we talk about "steel", we usually mean "steels"; broadly speaking, steels fall into four groups: carbon steels, alloy steels, tool steels, and stainless steels. These names can be confusing, because all alloy steels contain carbon (as do all other steels), all carbon steels are also alloys, and both tool steels and stainless steels are alloys too. Carbon steels The vast majority of steel produced each day (around 80–90 percent) is what we call carbon steel, though it contains only a tiny amount of carbon—sometimes much less than 1 percent. In other words, carbon steel is just basic, ordinary steel.

Steels with about 1–2 percent carbon are called (not surprisingly) high-carbon steels and, like cast-iron, they tend to be hard and brittle; steels with less than 1 percent carbon are known as low-carbon steels and like wrought iron, are softer and easier to shape. A huge range of different everyday items are made carbon steels, from car bodies and warship hulls to steel cans and engine parts. Alloy steels As well as iron and carbon, alloy steels contain one or more other elements, such as chromium , copper , manganese, nickel , silicon, or vanadium. In alloy steels, it's these extra elements that make the difference and provide some important additional feature or improved property compared to ordinary carbon steels. Alloy steels are generally stronger, harder, tougher, and more durable than carbon steels. Tool steels Tool steels are especially hard alloy steels used to make tools, dies, and machine parts. They're made from iron and carbon with added elements such as nickel, molybdenum, or tungsten to give extra hardness and resistance to wear.

Tool steels are also toughened up by a process called tempering, in which steel is first heated to a high temperature, then cooled very quickly, then heated again to a lower temperature. Stainless steels The steel you probably see most often is stainless steel—used in household cutlery, scissors, and medical instruments. Stainless steels contain a high proportion of chromium and nickel , are very resistant to corrosion and other chemical reactions, and are easy to clean, polish, and sterilize. Making steel There are three main stages involved in making a steel product. First, you make the steel from iron. Second, you treat the steel to improve its properties (perhaps by tempering it or plating it with another metal). Finally, you roll or otherwise shape the steel into the finished product. Making steel from iron Most steel is made from pig iron (remember: that's an iron alloy containing up to 4 percent carbon) by one of several different processes designed to remove some of the carbon and (optionally) substitute one or more other elements.

The three main steelmaking processes are: Basic oxygen process (BOP): The steel is made in a giant egg-shaped container, open at the top, called a basic oxygen furnace, which is similar to an ordinary blast furnace, only it can rotate to one side to pour off the finished metal. The air draft used in a blast furnace is replaced with an injection of pure oxygen through a pipe called a lance. The basic idea is based on the Bessemer process developed by Sir Henry Bessemer in the 1850s. Open-hearth process (also called the regenerative open hearth): A bit like a giant fireplace in which pig iron, scrap steel, and iron ore are burned with limestone until they fuse together. More pig iron is added, the unwanted carbon combines with oxygen, the impurities are removed as slag and the iron turns to molten steel. Skilled workers sample the steel and continue the process until the iron has exactly the right carbon content to make a particular type of steel. Electric-furnace process: You don't cook your dinner with an open fire, so why make steel in such a primitive way?

That's the thinking behind the electric furnace, which uses electric arcs (effectively giant sparks) to melt pig iron or scrap steel. Since they're much more controllable, electric furnaces are generally used to make higher-specification alloy, carbon, and tool steels. Photo: Making steel for weaponry with the three-ton electric arc furnace at Rock Island Arsenal. Photo by Tony Lopez courtesy of Defense Imagery. Which countries produce the world's raw steel? Approximately 1.65 billion metric tons of steel are made worldwide each year. This chart shows estimated worldwide raw steel production figures for 2015. In the United States, there were 110 "minimill" steel plants in operation at the start of 2016 (down from 113 a year earlier) making a total of about 110 million tons of steel (slightly down from 114 million tons in 2015). Indiana (27 percent), Ohio (13 percent), Michigan (6 percent), and Pennsylvania (5 percent) together produce about half of all US steel. Source: US Geological Survey, Mineral Commodity Summaries, January 2016.

Making steel products Liquid steel made by one of these processes is cast into huge bars called ingots, each of which weighs anything from a couple of tons (in typical steel plants) to hundreds of tons (in really big plants making giant steel objects). The ingots are rolled and pressed to make three types of basic steel "building blocks" known as blooms (giant bars with square ends), slabs (blooms with rectangular ends), and billets (longer than blooms but with smaller square ends). These blocks are then shaped and worked to make all kinds of final steel products. The basic shaping process usually involves hot rolling (for example, reheating blooms and then rolling them over and over again to make them thinner). Girders are made by rolling steel then forcing it through dies or milling machines to make such things as beams for buildings and railroad tracks. Rollers that are very close together can be used to squeeze steel into extremely thin sheets. Pipes are made by wrapping sheets round into circles then forcing the two edges together so they fuse under pressure where they join. Shaped steel can be further treated in all kinds of ways.

For example, "tins" for food containers (which are mostly steel) are made by electroplating steel sheets with molten tin using the process of electrolysis (the reverse of the electro-chemical process that happens in batteries ). Steel that needs to be especially resistant to weathering can be galvanized (dipped into a hot bath of molten zinc so it acquires an overall protective coating). Why is one type of iron and steel harder or softer than another? In all this discussion of iron and steel, you'll have noticed that different types behave almost like completely different materials under different conditions. What makes one form of iron or steel different from another? Why are some very hard and brittle while others are relatively soft and malleable (easy to work)? Peer at the internal structure of iron or steel under an electron microscope and you'll see that the answer largely boils down to how much carbon the iron contains and how it's distributed. Iron and steel consist of grains made of different kinds of iron and carbon, some of which are hard, while others are soft.

When the harder kinds predominate, you get a hard and brittle material; when there are more softer kinds in between, the material can bend and flex so you can work and shape it more easily. ? The compounds inside iron and steel include some or all of the following: Ferrite: Relatively pure iron with tiny amounts of carbon that is soft and easy to shape. Gives iron its magnetic property. Cementite (iron carbide): Iron with much more carbon (and sometimes other elements) that is very hard and brittle. Essentially behaves like a ceramic material. Graphite: Pure carbon crystals, which make iron alloys hard and brittle. Pearlite: A mixture made of alternate layers of ferrite and cementite that looks like mother of pearl under a microscope (hence the name "pearlite"). Austenite: An alloy of iron and carbon present in steel heated to high temperatures. Martensite: Similar to ferrite but much harder. Different types of iron and steel contain different amounts of these ingredients arranged in varying crystalline structures. Making iron alloys or steel by one method or another will change the relative amounts of the ingredients, altering its properties.

Treating steel in different ways after it's made changes its physical properties by altering its internal crystalline structure. For example, heat-treating steel changes austenite inside it into martensite, making its internal structure very much harder. Hammering and rolling steel breaks up crystals of graphite and other impurities lurking inside it, closes up any gaps that could lead to weaknesses, and generally produces a more regular crystalline structure. What is steel used for? Steel is one of the most versatile materials, used in everything from jet engines to surgical instruments and from table knives to machine tools. Major consumers of steel include the automobile and shipbuilding industries, the construction industry, producers of food cans, and manufacturers of electrical appliances. Photo: The inner steel skeleton of a building under construction. Many buildings are "quietly" supported by a secret inner structure like this that becomes invisible once they're complete. A brief history of iron and steel 4000 BCE: Iron is first used for ornaments and decoration, probably in the Middle East. 2500 BCE: Iron is used on a large scale for the first time by the Hittites, in a region now occupied by Turkey and Syria.

1200 BCE: Wrought iron (similar to steel) is developed. 1000 BCE: Iron Age begins: iron is widely used for making tools and weapons in many parts of the world. 200 BCE: Cast-iron objects are produced in China. 300BCE–400CE: First steel furnaces used in Africa, India, and China. 500–1000 CE: Blacksmiths make many important iron goods including weapons, plows, and horseshoes. 700: An efficient iron-making furnace called the Catalan forge is developed in Spain. 1200–1500: Blast furnaces powered by waterwheels become popular. 1709: Abraham Darby first uses coke (a type of coal) to make pig iron in Coalbrookdale in Shropshire in England's Midlands. His grandson, Abraham Darby III, uses cast iron to make a famous iron bridge at a place now called "Ironbridge," widely considered the heart of the English Industrial Revolution. 1856: Henry Bessemer announces his invention of the Bessemer converter, a basic oxygen furnace that can convert iron to steel in very large, commercial quantities.

1861: The brothers William and Frederick Siemens develop the open-hearth furnace 1879: William Siemens invents the electric furnace. 1954: Modern basic oxygen process is invented. Metals On other websites USGS Minerals Information: Iron and steel : Current statistics and other information about US and worldwide iron and steel production. American Iron and Steel Institute : Leading US trade organization. Website contains some simple background information about how we use steel today. Association for Iron & Steel Technology : Quite detailed background, though some sections of the site are for members only. Books General books for older readers Dreams of Iron and Steel by Deborah Cadbury. HarperCollins, 2004. Surveys seven "wonders of the modern world" made possible by iron and steel technology, including the Panama Canal, the London sewers, the Brooklyn Bridge, and the Hoover Dam. Stuff Matters by Mark Miodownik. Penguin, 2014. A friendly introduction to essential everyday materials.

Steel is covering in Chapter 1, "Indomitable." Iron - Element information, properties and uses | Periodic Table Chemistry in its element: iron (Promo) You're listening to Chemistry in its element brought to you by Chemistry World, the magazine of the Royal Society of Chemistry. (End promo) Chris Smith Hello, this week we turn to one of the most important elements in the human body. It's the one that makes metabolism possible and don't we just know it. There are iron man challenges, iron fisted leaders and those said to have iron in the soul. But there's a dark side to element number 26 too because its powerful chemistry means that it's also bad news for brain cells as Nobel Laureate Kary Mullis explains Kary Mullis For the human brain, iron is essential yet deadly. It exists on Earth mainly in two oxidation states - FeII and FeIII. FeIII is predominant within a few meters of the atmosphere which about two billion years ago turned 20% oxygen - oxidizing this iron to the plus three state which is virtually insoluble in water. This change from the relatively plentiful and soluble FeII, took a heavy toil on almost everything alive at the time.

Surviving terrestrial and ocean-dwelling microbes developed soluble siderophore molecules to regain access to this plentiful, but otherwise inaccessible essential resource, which used hydroxamate or catechol chelating groups to bring the FeIII back into solution. Eventually higher organisms including animals, evolved. And animals used the energy of oxygen recombining with the hydrocarbons and carbohydrates in plant life to enable motion. Iron was essential to this process. But no animal, however, has been able to adequately deal, in the long run - meaning eighty year life spans - with the fact that iron is essential for the conversion of solar energy to movement, but is virtually insoluble in water at neutral pH, and, even worse, is toxic. Carbon, sulfur, nitrogen. calcium, magnesium, sodium, maybe ten other elements are also involved in life, but none of them have the power of iron to move electrons around, and none of them have the power to totally destroy the whole system. Iron does. Systems have evolved to maintain iron in specific useful and safe configurations - enzymes which utilize its catalytic powers, or transferrins and haemosiderins, which move it around and store it. But these are not perfect.

Sometimes iron atoms are misplaced, and there are no known systems to recapture iron that has precipitated inside of a cell. In some tissues, cells overloaded with iron can be recycled or destroyed - but this doesn't work for neurons. Neurons sprout thousands of processes during their existence - reaching out to form networks of connections to other neurons. During development of the adult human brain a large percentage of cells are completely eliminated, and some new ones are added. It is a learning process. But once an area of the brain is up and running, there is nothing that can be done biologically, if a large number of its cells stop working for any reason. And the slow creep of precipitating iron over many decades is perhaps most often that reason. In less sophisticated tissues, like the liver, new stem cells can be activated, but in the brain, trained, structurally complex, interconnected neurons are needed, with thousands of projections that are accumulated over a lifetime of learning. So the result is slowly progressive neurodegenerative disease, like Parkinson's and Alzheimer's. This same basic mechanism can result in a variety of diseases. There are twenty or thirty proteins that that deal with iron in the brain - holding iron and passing it from place to place.

Every new individual endowed with a new set of chromosomes is endowed with a new set of these proteins. Some combinations will be better than others and some will be dangerous individually and collectively. A mutation in a gene that codes for one of these proteins could disrupt its function - allowing iron atoms to become lost. These atoms that have been lost from the chemical groups that hold them will not always be safely returned to some structure like transferrin or haemoferritin. Some of them will react with water and be lost forever. Only they aren't really lost. They are piling up in the unlucky cell types that were the designated locations for expression of the most iron-leaky proteins. And oxides of iron are not just taking up critical space. Iron is very reactive. The infamous "Reactive Oxygen Species" which have been suspected of causing so many age related illnesses may just derive from various forms of iron. It is time for specialists trained in chemistry, and with an eye to the chemistry of iron, to pay some attention to neurodegenerative disease. Chris Smith Kary Mullis telling the story of iron, the element that we can't do without, but which at the same time could hold the key to our neurological downfall.

Next time on Chemistry in its Element Johnny Ball will tell the story of Marie Curie and the element that she discovered and then named after her homeland. Johnny Ball Pitchblende, a uranium bearing ore, seemed to be far too radio active than could be accounted for by the uranium. They sieved and sorted by hand ounce by ounce through tons of pitchblende in a drafty, freezing shed, before eventually tiny amounts of polonium were discovered. Chris Smith So be radioactive or at least podcast proactive and join us for the mysterious story of Polonium on next week's Chemistry in its Element. I'm Chris Smith, thank you for listening, see you next time. (Promo) Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by thenakedscientists.com . There's more information and other episodes of Chemistry in its element on our website at chemistryworld.org/elements . (End promo) Iron Element Facts Shell Structure: 2 8 14 2 Iron Discovery Discovery Date: Ancient Times Name: Iron derives its name from the Anglo-Saxon 'iren'. The element symbol , Fe, was shortened from the Latin word 'ferrum' meaning 'firmness'.

History: Ancient Egyptian iron objects have been dated to around 3500 B.C. These objects also contain approximately 8% nickel showing the iron may have originally been part of a meteorite. The "Iron Age" began around 1500 B.C. when the Hittites of Asia Minor began to smelt iron ore and make iron tools. Iron Physical Data State at room temperature (300 K): Solid Appearance: malleable, ductile, silvery metal Density : 7.870 g/cc (25 °C) Density at Melting Point: 6.98 g/cc Iron Uses Iron is vital to plant and animal life. Iron is the active part of the hemoglobin molecule our bodies use to transport oxygen from the lungs to the rest of the body. Iron metal is widely alloyed with other metals and carbon for a multiple commercial uses. Pig iron is an alloy containing about 3-5% carbon, with varying quantities of Si, S, P, and Mn. Pig iron is brittle, hard, and fairly fusible and is used to produce other iron alloys , including steel .

Wrought iron contains only a few tenths of a percent of carbon and is malleable, tough, and less fusible than pig iron. Wrought iron typically has a fibrous structure. Carbon steel is an iron alloy with carbon and small amounts of S, Si, Mn, and P. Alloy steels are carbon steels that contain additives such as chromium, nickel, vanadium, etc. Iron is the least expensive, most abundant, and most used of all metals. Miscellaneous Iron Facts Iron is the 4th most abundant element in the Earth's crust. The Earth's core is believed to be comprised primarily of iron. Pure iron is chemically reactive and corrodes rapidly, especially in moist air or at elevated temperatures. There are four allotropes of iron known as 'ferrites'. These are designated α-, β-, γ-, and δ- with transition points at 770, 928, and 1530 °C. The α- and β- ferrites have the same crystal structure, but when the α- form becomes the β- form, the magnetism disappears. The most common iron ore is hematite (Fe2O3 mostly).

Iron is also found in magnetite (Fe3O4) and taconite (a sedimentary rock containing more than 15% iron mixed with quartz). The top three countries that mine iron are Ukraine, Russia and China. China, Australia and Brazil lead the world in iron production. Many meteorites have been found to contain high levels of iron. Iron is found in the sun and other stars. Iron is an essential mineral for health, but too much iron is extremely toxic. Free iron in the blood reacts with peroxides to form free radicals that damage DNA, protein, lipids and other cellular components, leading to illness and sometimes death. 20 milligrams of iron per kilogram of body weight is toxic, while 60 milligrams per kilogram is lethal. Iron is essential for the development of brain development. Children with iron deficiencies show a lower ability to learn. The Elements of Steel . Streamliners: America's Lost Trains . WGBH American Experience | PBS Iron is the main ingredient in various forms of iron and steel, but the various types of metals contain other elements as well. Sometimes these elements are unwanted; other times they're intentionally added.

The Elements Used in Steel Carbon (C): Carbon, a nonmetallic element, forms a number of organic and inorganic compounds and can be found in coal, petroleum and limestone. It is the principle strengthening element in carbon steels and low-alloy steels. Atomic number 6, atomic weight 12.01115. Manganese (Mn): Manganese is a brittle, metallic element that exists in the ore of pyrolusite. When making steel, it reacts with sulfur and helps to increase the metal's resistance to heat. Atomic number 25, atomic weight 54.9380. Phosphorus (P): Phosphorus is a poisonous, nonmetallic element that helps protect metal surfaces from corrosion. Atomic number 15, atomic weight 30.9738. Sulfur (S): Sulfur is a nonmetallic element found mainly in volcanic and sedimentary deposits. Sulfur, in the form of iron sulfide, can cause steel to be too porous and prone to cracking. Atomic number 16, atomic weight 32.064.

Silicon (Si): Silicon is the second most abundant element in the earth's crust and can be found in rocks, sand and clay. It acts as a deoxidizer in steel production. Atomic number 14, atomic weight 28.086. Nickel (Ni): Nickel is a hard, metallic element that found in igneous rocks. Without nickel, stainless steel would be less resistant to heat and corrosion. Atomic number 28, atomic weight 58.71. Chromium (Cr): Chromium, a metallic element, is found in the earth's crust. It is used in the production of stainless steel to make the steel resistant to oxidation and corrosion. Atomic number 24, atomic weight 51.996. The Elements of Steel Composition (percent by mass) Cast Iron Q & A: Iron, Steel, and Rust | Department of Physics | University of Illinois at Urbana-Champaign University of Illinois at Urbana-Champaign Q & A: Iron, Steel, and Rust Learn more physics!

What is rust and what is the difference between iron and steel - Deborah Kisiel (age 11) Kanaka Creek Elementary School, Maple Ridge, B.C., Canada, A: Iron is a pure element. Every atom in a chunk of iron is an iron atom. Iron is nice, but it's not very strong. Steel is even better. To make steel, they melt down iron and mix in small amounts of other elements. There are different types of steel based on what they mix in and how much. Each type of steel has different advantages, such as stength, durability, chemical reactivity, and many other qualities. Typical elements that are added to iron to make steel include Carbon, Manganese, Silicon, Chromium, and Molybdenum. But most of the atoms of steel are still iron, because they only usually add in a few percent of other elements. Now comes rust. Many elements like to go through chemical reactions with other elements. Iron likes to react with oxygen to for iron-oxide...or rust. We can't keep oxygen away from the iron in our cars since much of the atmosphere is oxygen. Rust weakens the iron and can make parts break.

Steel has the same problem, but some of those elements that are added during the steel production can help prevent rust or at least slow it down. For example, "stainless steel" is designed so that it will not rust, but it is more expensive that other types of steel. Adam Steel Steel By Anne Marie Helmenstine, Ph.D. Steel is an alloy of iron that contains carbon . Typically the carbon content ranges from 0.002% and 2.1% by weight. Carbon makes steel harder than pure iron. The carbon atoms make it more difficult for dislocations in the iron crystal lattice to slide past each other. There are many different types of steel. Steel contains additional elements, either as impurities or added to confer desirable properties. Most steel contains manganese, phosphorus, sulfur, silicon, and trace amounts of aluminum, oxygen, and nitrogen. Intentionally addition of nickel, chromium, manganese, titanium, molybdenum, boron, niobium and other metals influence the hardness, ductility, strength, and other properties of steel.

Steel History The oldest piece of steel is a piece of ironware that was recovered from an archaeological site in Anatolia, dating back to about 2000 BC. Steel from ancient Africa dates back to 1400 BC. How Steel Is Made Steel contains iron and carbon, but when iron ore is smelted, it contains too much carbon to confer desirable properties for steel. continue reading below our video What are the Seven Wonders of the World Iron ore pellets are remelted and processed to reduce the amount of carbon. Then, additional elements are added and the steel is either continuously cast or made into ingots. Modern steel is made from pig iron using one of two processes. About 40% of steel is made using the basic oxygen furnace (BOF) process. In this process, pure oxygen is blown into melted iron, reducing the amounts of carbon, manganese, silicon, and phosphorus. Chemicals called fluxes further reduce levels of sulfur and phosphorus in the metal. In the United States, the BOF process recycles 25-35% scrap steel to make new steel.

In the U.S., the electric arc furnace (EAF) process is used to make about 60% of steel, consisting nearly entirely of recycled scrap steel. Learn More

Question: Which element is added to iron to make steel?
Answer: CARBON